Add Uint32 representation

runtime/vm/intermediate_language_ia32.cc

Index: runtime/vm/intermediate_language_ia32.cc
diff --git a/runtime/vm/intermediate_language_ia32.cc b/runtime/vm/intermediate_language_ia32.cc
index 457d62d73a4dcce751f1c4b3c656aa86a45f2c2a..2c6c36274c211172bc4d827f0d21ff69ad3be7fa 100644
--- a/runtime/vm/intermediate_language_ia32.cc
+++ b/runtime/vm/intermediate_language_ia32.cc
@@ -5613,8 +5613,12 @@ LocationSummary* UnboxIntegerInstr::MakeLocationSummary(Isolate* isolate,
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   summary->set_in(0, Location::RequiresRegister());
-  summary->set_out(0, Location::Pair(Location::RegisterLocation(EAX),
-                                     Location::RegisterLocation(EDX)));
+  if (is_32_bit()) {
+    summary->set_out(0, Location::RequiresRegister());
+  } else {
+    summary->set_out(0, Location::Pair(Location::RegisterLocation(EAX),
+                                       Location::RegisterLocation(EDX)));
+  }
   return summary;
 }
 
@@ -5622,6 +5626,33 @@ LocationSummary* UnboxIntegerInstr::MakeLocationSummary(Isolate* isolate,
 void UnboxIntegerInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   const intptr_t value_cid = value()->Type()->ToCid();
   const Register value = locs()->in(0).reg();
+
+  if (is_32_bit()) {
+    const Register out = locs()->out(0).reg();
+    if (value_cid == kMintCid) {
+      __ movl(out, FieldAddress(value, Mint::value_offset()));

[Vyacheslav Egorov (Google), 2014/06/23 20:02:06]

for constants here it is beneficial to emit immediate move, right now we waste
registers:

0xf66a8ef5    bf792a71f6             mov edi,0xf6712a79  '4294967295'
0xf66a8efa    8b4703                 mov eax,[edi+0x3]

+    } else if (value_cid == kSmiCid) {
+      __ movl(out, value);
+      __ SmiUntag(out);
+    } else {
+      Label* deopt = compiler->AddDeoptStub(deopt_id_,
+                                            ICData::kDeoptUnboxInteger);
+      Label is_smi, done;
+      __ testl(value, Immediate(kSmiTagMask));
+      __ j(ZERO, &is_smi);
+      __ CompareClassId(value, kMintCid, out);
+      __ j(NOT_EQUAL, deopt);
+      __ movl(out, FieldAddress(value, Mint::value_offset()));
+      __ jmp(&done);
+      __ Bind(&is_smi);
+      __ movl(out, value);
+      __ SmiUntag(out);
+      __ Bind(&done);
+    }
+    return;
+  }
+
+  ASSERT(!is_32_bit());
   PairLocation* result_pair = locs()->out(0).AsPairLocation();
   Register result_lo = result_pair->At(0).reg();
   Register result_hi = result_pair->At(1).reg();
@@ -5754,33 +5785,128 @@ void BoxIntegerInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 }
 
 
+LocationSummary* MintConverterInstr::MakeLocationSummary(Isolate* isolate,
+                                                         bool opt) const {
+  // We should only see this in optimized code.
+  ASSERT(opt);
+  const intptr_t kNumInputs = 1;
+  const intptr_t kNumTemps = 0;
+  LocationSummary* summary = new(isolate) LocationSummary(
+      isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
+  if (conversion_kind() == kMint32ToMint) {
+    summary->set_in(0, Location::RequiresRegister());
+    summary->set_out(0, Location::Pair(Location::RequiresRegister(),
+                                       Location::RequiresRegister()));
+  } else if (conversion_kind() == kMintToMint32) {
+    summary->set_in(0, Location::Pair(Location::RequiresRegister(),
+                                      Location::RequiresRegister()));
+    summary->set_out(0, Location::RequiresRegister());
+  } else {
+    UNREACHABLE();
+  }
+  return summary;
+}
+
+
+void MintConverterInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  if (conversion_kind() == kMint32ToMint) {
+    Register in = locs()->in(0).reg();
+    PairLocation* out_pair = locs()->out(0).AsPairLocation();
+    Register out_lo = out_pair->At(0).reg();
+    Register out_hi = out_pair->At(1).reg();
+    // Copy lo.
+    __ movl(out_lo, in);
+    // Zero hi.
+    __ xorl(out_hi, out_hi);
+  } else if (conversion_kind() == kMintToMint32) {
+    PairLocation* in_pair = locs()->in(0).AsPairLocation();
+    Register in_lo = in_pair->At(0).reg();
+    Register out = locs()->out(0).reg();
+    // Copy lo.
+    __ movl(out, in_lo);
+  } else {
+    UNREACHABLE();
+  }
+}
+
+
+static bool BinaryMintOutputSameAsInput(const BinaryMintOpInstr* instr) {
+  return instr->is_32_bit() == instr->IsInput32Bit(0);
+}
+
 LocationSummary* BinaryMintOpInstr::MakeLocationSummary(Isolate* isolate,

[Vyacheslav Egorov (Google), 2014/06/23 20:02:06]

This instruction became way too complex. We need to split it into pieces if
possible.

It is also seemingly emitting some strange move:

        ;; v9 <- BinaryMintOp:34(-, v17, v18, v21, v22) [0, 4294967295]
T{not-null, dynamic, Type: class 'int'} 32-BIT
0xf665df00    89d0                   mov eax,edx
0xf665df02    2bc3                   sub eax,ebx

Should not the register allocator take care of copying input only if necessary?
We should have smth like "sub edx, ebx" here

                                                         bool opt) const {
   const intptr_t kNumInputs = 2;
+  // Need a temporary right high word if we are computing a 64-bit value
+  // and the right operand is 32-bits.
+  const intptr_t kNumTemps = (!is_32_bit() && IsInput32Bit(1)) ? 1 : 0;
   switch (op_kind()) {
     case Token::kBIT_AND:
     case Token::kBIT_OR:
     case Token::kBIT_XOR: {
-      const intptr_t kNumTemps = 0;
       LocationSummary* summary = new(isolate) LocationSummary(
           isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
-      summary->set_in(0, Location::Pair(Location::RequiresRegister(),
-                                        Location::RequiresRegister()));
-      summary->set_in(1, Location::Pair(Location::RequiresRegister(),
-                                        Location::RequiresRegister()));
-      summary->set_out(0, Location::SameAsFirstInput());
+
+      if (kNumTemps > 0) {
+        ASSERT(kNumTemps == 1);
+        summary->set_temp(0, Location::RequiresRegister());
+      }
+
+      if (IsInput32Bit(0)) {
+        summary->set_in(0, Location::RequiresRegister());
+      } else {
+        summary->set_in(0, Location::Pair(Location::RequiresRegister(),
+                                          Location::RequiresRegister()));
+      }
+
+      if (IsInput32Bit(1)) {
+        summary->set_in(1, Location::RequiresRegister());
+      } else {
+        summary->set_in(1, Location::Pair(Location::RequiresRegister(),
+                                  Location::RequiresRegister()));
+      }
+
+      if (BinaryMintOutputSameAsInput(this)) {
+        summary->set_out(0, Location::SameAsFirstInput());
+      } else if (is_32_bit()) {
+        summary->set_out(0, Location::RequiresRegister());
+      } else {
+        summary->set_out(0, Location::Pair(Location::RequiresRegister(),
+                                           Location::RequiresRegister()));
+      }
       return summary;
     }
     case Token::kADD:
     case Token::kSUB: {
-      const intptr_t kNumTemps = 0;
       LocationSummary* summary = new(isolate) LocationSummary(
           isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
-      summary->set_in(0, Location::Pair(Location::RequiresRegister(),
-                                        Location::RequiresRegister()));
-      summary->set_in(1, Location::Pair(Location::RequiresRegister(),
-                                        Location::RequiresRegister()));
-      summary->set_out(0, Location::SameAsFirstInput());
+
+      if (kNumTemps > 0) {
+        ASSERT(kNumTemps == 1);
+        summary->set_temp(0, Location::RequiresRegister());
+      }
+      if (IsInput32Bit(0)) {
+        summary->set_in(0, Location::RequiresRegister());
+      } else {
+        summary->set_in(0, Location::Pair(Location::RequiresRegister(),
+                                          Location::RequiresRegister()));
+      }
+
+      if (IsInput32Bit(1)) {
+        summary->set_in(1, Location::RequiresRegister());
+      } else {
+        summary->set_in(1, Location::Pair(Location::RequiresRegister(),
+                                          Location::RequiresRegister()));
+      }
+
+      if (BinaryMintOutputSameAsInput(this)) {
+        summary->set_out(0, Location::SameAsFirstInput());
+      } else if (is_32_bit()) {
+        summary->set_out(0, Location::RequiresRegister());
+      } else {
+        summary->set_out(0, Location::Pair(Location::RequiresRegister(),
+                                           Location::RequiresRegister()));
+      }
       return summary;
     }
     default:
@@ -5791,17 +5917,83 @@ LocationSummary* BinaryMintOpInstr::MakeLocationSummary(Isolate* isolate,
 
 
 void BinaryMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  PairLocation* left_pair = locs()->in(0).AsPairLocation();
-  Register left_lo = left_pair->At(0).reg();
-  Register left_hi = left_pair->At(1).reg();
-  PairLocation* right_pair = locs()->in(1).AsPairLocation();
-  Register right_lo = right_pair->At(0).reg();
-  Register right_hi = right_pair->At(1).reg();
+  Register left_lo = kNoRegister;
+  Register left_hi = kNoRegister;
+  Register right_lo = kNoRegister;
+  Register right_hi = kNoRegister;
+  Register out_lo = kNoRegister;
+  Register out_hi = kNoRegister;
+
+  if (IsInput32Bit(0)) {
+    left_lo = locs()->in(0).reg();
+  } else {
+    PairLocation* left_pair = locs()->in(0).AsPairLocation();
+    left_lo = left_pair->At(0).reg();
+    left_hi = left_pair->At(1).reg();
+  }
+
+  if (IsInput32Bit(1)) {
+    right_lo = locs()->in(1).reg();
+  } else {
+    PairLocation* right_pair = locs()->in(1).AsPairLocation();
+    right_lo = right_pair->At(0).reg();
+    right_hi = right_pair->At(1).reg();
+  }
+
+  if (is_32_bit()) {
+    out_lo = locs()->out(0).reg();
+    if (!BinaryMintOutputSameAsInput(this)) {
+      // Copy lo part of left.
+      __ movl(out_lo, left_lo);
+    } else {
+      ASSERT(out_lo == left_lo);
+    }
+    switch (op_kind()) {
+      case Token::kBIT_AND:
+        __ andl(out_lo, right_lo);
+        break;
+      case Token::kBIT_OR:
+        __ orl(out_lo, right_lo);
+        break;
+      case Token::kBIT_XOR:
+        __ xorl(out_lo, right_lo);
+        break;
+      case Token::kADD:
+      case Token::kSUB: {
+        if (op_kind() == Token::kADD) {
+          __ addl(out_lo, right_lo);
+        } else {
+          __ subl(out_lo, right_lo);
+        }
+        break;
+      }
+      default: UNREACHABLE();
+    }
+    return;
+  }
+
+  ASSERT(!is_32_bit());
+
   PairLocation* out_pair = locs()->out(0).AsPairLocation();
-  Register out_lo = out_pair->At(0).reg();
-  Register out_hi = out_pair->At(1).reg();
-  ASSERT(out_lo == left_lo);
-  ASSERT(out_hi == left_hi);
+  out_lo = out_pair->At(0).reg();
+  out_hi = out_pair->At(1).reg();
+  if (BinaryMintOutputSameAsInput(this)) {
+    ASSERT(out_lo == left_lo);
+    ASSERT(out_hi == left_hi);
+  } else {
+    // Left input is 32-bits.
+    ASSERT(IsInput32Bit(0));
+    // Copy lo input.
+    __ movl(out_lo, left_lo);
+    // Zero output.
+    __ xorl(out_hi, out_hi);
+  }
+
+  if (IsInput32Bit(1)) {
+    // Zero temporary right high word.
+    right_hi = locs()->temp(0).reg();
+    __ xorl(right_hi, right_hi);
+  }
 
   Label* deopt = NULL;
   if (FLAG_throw_on_javascript_int_overflow) {
@@ -5809,16 +6001,16 @@ void BinaryMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   }
   switch (op_kind()) {
     case Token::kBIT_AND:
-      __ andl(left_lo, right_lo);
-      __ andl(left_hi, right_hi);
+      __ andl(out_lo, right_lo);
+      __ andl(out_hi, right_hi);
       break;
     case Token::kBIT_OR:
-      __ orl(left_lo, right_lo);
-      __ orl(left_hi, right_hi);
+      __ orl(out_lo, right_lo);
+      __ orl(out_hi, right_hi);
       break;
     case Token::kBIT_XOR:
-      __ xorl(left_lo, right_lo);
-      __ xorl(left_hi, right_hi);
+      __ xorl(out_lo, right_lo);
+      __ xorl(out_hi, right_hi);
       break;
     case Token::kADD:
     case Token::kSUB: {
@@ -5826,11 +6018,11 @@ void BinaryMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
         deopt  = compiler->AddDeoptStub(deopt_id(), ICData::kDeoptBinaryMintOp);
       }
       if (op_kind() == Token::kADD) {
-        __ addl(left_lo, right_lo);
-        __ adcl(left_hi, right_hi);
+        __ addl(out_lo, right_lo);
+        __ adcl(out_hi, right_hi);
       } else {
-        __ subl(left_lo, right_lo);
-        __ sbbl(left_hi, right_hi);
+        __ subl(out_lo, right_lo);
+        __ sbbl(out_hi, right_hi);
       }
       __ j(OVERFLOW, deopt);
       break;
@@ -5838,71 +6030,157 @@ void BinaryMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
     default: UNREACHABLE();
   }
   if (FLAG_throw_on_javascript_int_overflow) {
-    EmitJavascriptIntOverflowCheck(compiler, deopt, left_lo, left_hi);
+    EmitJavascriptIntOverflowCheck(compiler, deopt, out_lo, out_hi);
   }
 }
 
 
+static bool ShiftMintOpInstrOutputSameAsInput(const ShiftMintOpInstr* instr) {
+  return instr->is_32_bit() == instr->IsInput32Bit(0);
+}
+
+
 LocationSummary* ShiftMintOpInstr::MakeLocationSummary(Isolate* isolate,
                                                        bool opt) const {
+  const bool need_temps = (op_kind() == Token::kSHL) && CanShiftLeftOverflow();
   const intptr_t kNumInputs = 2;
-  const intptr_t kNumTemps = op_kind() == Token::kSHL ? 2 : 0;
+  const intptr_t kNumTemps = need_temps ? 2 : 0;
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
-  summary->set_in(0, Location::Pair(Location::RequiresRegister(),
-                                    Location::RequiresRegister()));
+
+
+  if (IsInput32Bit(0)) {
+    summary->set_in(0, Location::RequiresRegister());
+  } else {
+    summary->set_in(0, Location::Pair(Location::RequiresRegister(),
+                                      Location::RequiresRegister()));
+  }
+
   summary->set_in(1, Location::RegisterLocation(ECX));
-  if (op_kind() == Token::kSHL) {
+
+  if (need_temps) {
     summary->set_temp(0, Location::RequiresRegister());
     summary->set_temp(1, Location::RequiresRegister());
   }
-  summary->set_out(0, Location::SameAsFirstInput());
+
+  if (ShiftMintOpInstrOutputSameAsInput(this)) {
+    summary->set_out(0, Location::SameAsFirstInput());
+  } else if (is_32_bit()) {
+    summary->set_out(0, Location::RequiresRegister());
+  } else {
+    ASSERT(IsInput32Bit(0));
+    summary->set_out(0, Location::Pair(Location::RequiresRegister(),
+                                       Location::RequiresRegister()));
+  }
+
   return summary;
 }
 
 
 void ShiftMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  PairLocation* left_pair = locs()->in(0).AsPairLocation();
-  Register left_lo = left_pair->At(0).reg();
-  Register left_hi = left_pair->At(1).reg();
-  PairLocation* out_pair = locs()->out(0).AsPairLocation();
-  Register out_lo = out_pair->At(0).reg();
-  Register out_hi = out_pair->At(1).reg();
-  ASSERT(out_lo == left_lo);
-  ASSERT(out_hi == left_hi);
+  // Shift count is in ECX.
+  ASSERT(locs()->in(1).reg() == ECX);
+  Register left_lo;
+  Register left_hi;
+  Register out_lo;
+  Register out_hi;
+
+  if (IsInput32Bit(0)) {
+    left_lo = locs()->in(0).reg();
+    left_hi = kNoRegister;
+  } else {
+    PairLocation* left_pair = locs()->in(0).AsPairLocation();
+    left_lo = left_pair->At(0).reg();
+    left_hi = left_pair->At(1).reg();
+  }
+
+  if (is_32_bit()) {
+    out_lo = locs()->out(0).reg();
+    out_hi = kNoRegister;
+  } else {
+    PairLocation* out_pair = locs()->out(0).AsPairLocation();
+    out_lo = out_pair->At(0).reg();
+    out_hi = out_pair->At(1).reg();
+  }
+
+  if (ShiftMintOpInstrOutputSameAsInput(this)) {
+    ASSERT(out_lo == left_lo);
+    ASSERT(out_hi == left_hi);
+  } else if (is_32_bit()) {
+    ASSERT(!IsInput32Bit(0));
+    // Copy lo.
+    __ movl(out_lo, left_lo);
+  } else if (IsInput32Bit(0)) {
+    ASSERT(!is_32_bit());
+    // Copy lo.
+    __ movl(out_lo, left_lo);
+    // Zero hi.
+    __ xorl(out_hi, out_hi);
+  }
+
 
-  Label* deopt = compiler->AddDeoptStub(deopt_id(), ICData::kDeoptShiftMintOp);
   Label done;
   __ testl(ECX, ECX);
   __ j(ZERO, &done);  // Shift by 0 is a nop.
+  __ SmiUntag(ECX);
+
   // Deoptimize if shift count is > 31.
   // sarl operation masks the count to 5 bits and
   // shrd is undefined with count > operand size (32)
   // TODO(fschneider): Support shift counts > 31 without deoptimization.
-  __ SmiUntag(ECX);
+
+  Label* deopt = compiler->AddDeoptStub(deopt_id(), ICData::kDeoptShiftMintOp);
   const Immediate& kCountLimit = Immediate(31);
   __ cmpl(ECX, kCountLimit);
   __ j(ABOVE, deopt);
+
   switch (op_kind()) {
     case Token::kSHR: {
-      __ shrd(left_lo, left_hi);  // Shift count in CL.
-      __ sarl(left_hi, ECX);  // Shift count in CL.
+      if (IsInput32Bit(0)) {
+        // 32-bit input.
+        // Upper word is 0, use logical shift.
+        __ shrl(out_lo, ECX);
+        // If needed, out_hi is already zero.
+      } else {
+        // 64-bit input,
+        if (is_32_bit()) {
+          // 32-bit output
+          __ shrd(out_lo, left_hi);  // Shift count in CL.
+        } else {
+          // 64-bit output.
+          __ shrd(out_lo, left_hi);  // Shift count in CL.
+          __ sarl(out_hi, ECX);  // Shift count in CL.
+        }
+      }
       break;
     }
     case Token::kSHL: {
-      Register temp1 = locs()->temp(0).reg();
-      Register temp2 = locs()->temp(1).reg();
-      __ movl(temp1, left_lo);  // Low 32 bits.
-      __ movl(temp2, left_hi);  // High 32 bits.
-      __ shll(left_lo, ECX);  // Shift count in CL.
-      __ shld(left_hi, temp1);  // Shift count in CL.
-      // Check for overflow by shifting back the high 32 bits
-      // and comparing with the input.
-      __ movl(temp1, temp2);
-      __ movl(temp2, left_hi);
-      __ sarl(temp2, ECX);
-      __ cmpl(temp1, temp2);
-      __ j(NOT_EQUAL, deopt);
+      if (CanShiftLeftOverflow()) {
+        // 64-bit input and 64-bit output.
+        Register temp1 = locs()->temp(0).reg();
+        Register temp2 = locs()->temp(1).reg();
+        __ movl(temp1, out_lo);  // Low 32 bits.
+        __ movl(temp2, out_hi);  // High 32 bits.
+        __ shll(out_lo, ECX);  // Shift count in CL.
+        __ shld(out_hi, temp1);  // Shift count in CL.
+        // Check for overflow by shifting back the high 32 bits
+        // and comparing with the input.
+        __ movl(temp1, temp2);
+        __ movl(temp2, out_hi);
+        __ sarl(temp2, ECX);
+        __ cmpl(temp1, temp2);
+        __ j(NOT_EQUAL, deopt);
+      } else {
+        if (is_32_bit()) {
+          // 32-bit output (can be 64-bit or 32-bit input).
+          __ shll(out_lo, ECX);
+        } else {
+          // 64-bit output and 32-bit input.
+          ASSERT(out_lo != left_lo);
+          __ shll(out_lo, ECX);
+          __ shld(out_hi, left_lo);
+        }
+      }
       break;
     }
     default:
@@ -5910,23 +6188,40 @@ void ShiftMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
       break;
   }
   __ Bind(&done);
-  if (FLAG_throw_on_javascript_int_overflow) {
-    EmitJavascriptIntOverflowCheck(compiler, deopt, left_lo, left_hi);
+  if (FLAG_throw_on_javascript_int_overflow && !is_32_bit()) {
+    EmitJavascriptIntOverflowCheck(compiler, deopt, out_lo, out_hi);
   }
 }
 
 
+static bool UnaryMintOutputSameAsInput(const UnaryMintOpInstr* instr) {
+  return instr->is_32_bit() == instr->IsInput32Bit(0);
+}
+
+
 LocationSummary* UnaryMintOpInstr::MakeLocationSummary(Isolate* isolate,
                                                        bool opt) const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 0;
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
-  summary->set_in(0, Location::Pair(Location::RequiresRegister(),
-                                    Location::RequiresRegister()));
-  summary->set_out(0, Location::SameAsFirstInput());
-  if (FLAG_throw_on_javascript_int_overflow) {
-    summary->set_temp(0, Location::RequiresRegister());
+
+  if (IsInput32Bit(0)) {
+    summary->set_in(0, Location::RequiresRegister());
+  } else {
+    summary->set_in(0, Location::Pair(Location::RequiresRegister(),
+                                      Location::RequiresRegister()));
+  }
+
+  if (UnaryMintOutputSameAsInput(this)) {
+    summary->set_out(0, Location::SameAsFirstInput());
+  } else if (IsInput32Bit(0)) {
+    ASSERT(!is_32_bit());
+    summary->set_out(0, Location::Pair(Location::RequiresRegister(),
+                                       Location::RequiresRegister()));
+  } else {
+    ASSERT(is_32_bit());
+    summary->set_out(0, Location::RequiresRegister());
   }
   return summary;
 }
@@ -5934,25 +6229,52 @@ LocationSummary* UnaryMintOpInstr::MakeLocationSummary(Isolate* isolate,
 
 void UnaryMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   ASSERT(op_kind() == Token::kBIT_NOT);
-  PairLocation* left_pair = locs()->in(0).AsPairLocation();
-  Register left_lo = left_pair->At(0).reg();
-  Register left_hi = left_pair->At(1).reg();
-  PairLocation* out_pair = locs()->out(0).AsPairLocation();
-  Register out_lo = out_pair->At(0).reg();
-  Register out_hi = out_pair->At(1).reg();
-  ASSERT(out_lo == left_lo);
-  ASSERT(out_hi == left_hi);
+
+  // Extract registers.
+  Register out_lo;
+  Register out_hi = kNoRegister;
+  Register left_lo;
+  Register left_hi = kNoRegister;
+
+  if (IsInput32Bit(0)) {
+    left_lo = locs()->in(0).reg();
+  } else {
+    PairLocation* left_pair = locs()->in(0).AsPairLocation();
+    left_lo = left_pair->At(0).reg();
+    left_hi = left_pair->At(1).reg();
+  }
+
+  if (is_32_bit()) {
+    out_lo = locs()->out(0).reg();
+  } else {
+    PairLocation* out_pair = locs()->out(0).AsPairLocation();
+    out_lo = out_pair->At(0).reg();
+    out_hi = out_pair->At(1).reg();
+  }
+
+  if (UnaryMintOutputSameAsInput(this)) {
+    ASSERT(out_lo == left_lo);
+    ASSERT(out_hi == left_hi);
+  } else {
+    __ movl(out_lo, left_lo);
+    if (!is_32_bit() && IsInput32Bit(0)) {
+      // Zero high word.
+      __ xorl(out_hi, out_hi);
+    }
+  }
 
   Label* deopt = NULL;
-  if (FLAG_throw_on_javascript_int_overflow) {
+  if (FLAG_throw_on_javascript_int_overflow && !is_32_bit()) {
     deopt = compiler->AddDeoptStub(deopt_id(), ICData::kDeoptUnaryMintOp);
   }
 
-  __ notl(left_lo);
-  __ notl(left_hi);
+  __ notl(out_lo);
+  if (!is_32_bit()) {
+    __ notl(out_hi);
+  }
 
-  if (FLAG_throw_on_javascript_int_overflow) {
-    EmitJavascriptIntOverflowCheck(compiler, deopt, left_lo, left_hi);
+  if (FLAG_throw_on_javascript_int_overflow && !is_32_bit()) {
+    EmitJavascriptIntOverflowCheck(compiler, deopt, out_lo, out_hi);
   }
 }